1. Field of the Invention
The present invention relates to a circuit arrangement for the control of a ventilator, especially for a steam or vapor vent hood which is located above a cooking range, in dependence upon steam or vapor clouds which are drawn towards the ventilator. 2. Discussion of the Prior Art
A vapor or steam vent hood with a controllable blower motor is described in the disclosure of German Laid-Open Patent Appln. 30 39 346 A1. Arranged on this hood is a sensor element which is responsive to moisture and/or steam and and/or smoke and/or heat. This sensor element; for example, may consist of a moisture probe, a temperature probe or a probe which is responsive to particles.
In the disclosure of German Published Patent Appln. 25 18 750 there is described a steam vapor vent hood, whose ventilator is activated in dependence upon a temperature differential which is present between the temperature of the cooking vapors and the temperature of the surroundings thereof.
The disclosure of German Petty Patent 76 33 882 pertains to a steam or vapor vent hood, whose ventilator is activated through the intermediary of a moisture probe.
In the disclosure of U.S. Pat. No. 3,625,135 there is described a steam or vapor vent hood, whose ventilator is activated in dependence upon particles which are encountered in the cooking vapors.
It has been evidenced in the technology that a temperature-dependent control of the ventilator is subject to problems inasmuch as the temperature in the steam or vapor clouds which are present in the region of the steam vent hood is not so significantly higher than the temperature of the surroundings so as to enable this differnece to be easily employed for the control of the ventilator. Moisture probes or particle probes or sensors also do not lead in a simple manner to the desired control. In addition thereto, such probes are complex and expensive in their construction.
In accordance with the disclosure of German Patent 32 45 302, the steam or vapor vent hood is not controlled in dependence upon the steam or vapor clouds which are drawn towards the ventilator. In contrast therewith, the steam vent hood is controlled through the intermediary of a photoelectric sensor by means of a photoelectric signal transmitter on the cooking range.